New Build - left channel mia

[doctorcilantro]

I'm thinking of building a CRACK.

Wondering if anyone knows why the 5814 is claimed to be a custom-made more-linear 12AU7 when all the operating parameters appear to identical, rather than the E80CC.

cheers!
DC

[Paul Joppa]

5814 is a "special quality" tube, and rated for high vibration. It draws a bit more heater current but not much - 350mA instead of 300mA. My guess is a larger heater for longer life, and more mica supports for the tube elements, but otherwise the same mechanical design and probably the same tooling. It's rated for quite a wide variety of things, including channel balance - look up the RCA data sheet for more information than anyone really wants!

E80CC is quite a different tube, requiring twice the heater current and having 60% more gain - mu is 27 instead of 17.

[Paul Birkeland]

If all the voltages are OK, that tells me the tubes are working fine.

I would short the output terminals of the attenuator together to see if that is the problem.

Also try bypassing the coupling cap on the offending channel to see if that helps.

[doctorcilantro]

I meant to post this is another thread; did not mean to hijack it momentarily. Sorry bout that. (I swear I have seen data sheets with the heater current at 300mA for 5814 - will have to double-check).

5814 is a "special quality" tube, and rated for high vibration. It draws a bit more heater current but not much - 350mA instead of 300mA. My guess is a larger heater for longer life, and more mica supports for the tube elements, but otherwise the same mechanical design and probably the same tooling. It's rated for quite a wide variety of things, including channel balance - look up the RCA data sheet for more information than anyone really wants!

E80CC is quite a different tube, requiring twice the heater current and having 60% more gain - mu is 27 instead of 17.